Methiozolin [5-(2,6-difluorobenzyl)oxymethyl-5-methyl-3,3(3-methylthiophen-2-yl)-1,2-isoxazoline], a new annual bluegrass (Poa annuaL.) herbicide for turfgrasses

Abstract

Selective control of annual bluegrass (Poa annual L.) has been difficult in turfgrasses. The potential of methiozolin in this area was investigated. Methiozolin was safe on established zoysiagrass (Zoysia japonica Steud.), creeping bentgrass (Agrostis palustris Huds.), Kentucky bluegrass (Poa pratensis L.), and perennial ryegrass (Lolium perenne L.) at 1000 g ha(-1) , and controlled annual bluegrass with GR50 values of 23, 52, 104, and 218 g ha(-1) at PRE, two-, four- and eight-leaf stage, respectively, in the greenhouse. When applied at early flowering, methiozolin suppressed >80% of annual bluegrass seed heads at 2000 g ha(-1) . (14) C-Methiozolin was readily absorbed by both leaves and roots, but translocation was mainly acropetal. No herbicidal activity resulted from application to the leaf only; however, application to the soil surface only showed equivalent herbicidal activity to that of broadcast application to the leaf and soil. Methiozolin at 500 to 1000 g ha(-1) provided 80 to 100% control of annual bluegrass when applied in the fall with acceptable and temporary injury to creeping bentgrass, and about 60% control when applied in the spring with no bentgrass injury in the field. Methiozolin is an excellent candidate for annual bluegrass management in turfgrasses.